Chambered doctor blade units for inkers for printing machines are well known; customarily, they include an essentially open box-like structure forming a bottom wall, a top wall, a rear wall, and side walls. Doctor blades, scrapers, or stripping elements are set in or attached to the top and bottom walls, or the doctor blade units themselves are made with surfaces functioning as stripping elements, positioned for engagement with, or closely adjacent the printing machine roller, for example and anilox roller, with which they are to cooperate. The side walls, directly or by way of inserts, have a curved surface which extends towards the printing machine roller, with a radius of curvature corresponding generally to that of the cooperating roller. It has been customary to construct the side walls of such inkers parallel to each other, and perpendicular to the axis of rotation of the roller with which they are to cooperate. It has been found that overpressure of ink between the roller of the printing machine and the associated end surfaces of the side walls has the tendency to squeeze or press ink outside of the side walls. This is particularly apparent in inkers in which the side walls do not have an elastic sealing strip or any sealing arrangement to seal the side walls against the printing machine roller has been worn; some doctor blade units also use side walls which have a slight clearance from the inker roller.